Outside the Israeli city of Ashkelon, dozens of Merkava tanks stand in a broad field lined with olive trees, their guns pointing towards the Gaza Strip less than five miles away.

In the coming days or even hours, Israel’s leaders will have to decide whether to order these mighty machines of war to advance into Gaza and transform Operation Protective Edge from an air to a ground offensive.

If so, the casualties and risks of the campaign against Hamas would inevitably rise. Benjamin Netanyahu is a cautious prime minister, deeply reluctant to send troops and tanks to fight in Gaza. But he may no longer be able to resist the pressure.

Israel saw Hamas’s rejection of the Egyptian ceasefire proposal as clear evidence of an intention to escalate - and Mr Netanyahu’s right-wing colleagues argue that he has no choice but to follow suit.

Already, the prime minister has been roundly criticised for accepting the ceasefire on Tuesday. Hawks believe that he gave Hamas a breathing space and allowed them to look resolute when he ordered Israeli forces to hold fire for six hours.

Israeli firefighters extinguish a blaze caused by crashing rocket fired from the Gaza Strip into Ashkelon, close to the Gaza border in Israel (EPA)

In the security cabinet, Avigdor Lieberman, the foreign minister, and Naftali Bennett, the economy minister, are both arguing for a ground attack. So is General Shlomo Turjeman, the head of Israel’s Southern Command and the man who would actually have to carry it out.

Danny Danon, the deputy defence minister and a member of the prime minister’s Likud party, was sacked on Tuesday after saying that his master had failed to let the army “do what it must”.

General Giora Eiland, a former national security adviser, told the Telegraph that a ground attack would inflict more damage on Hamas than any air campaign. More targets could be located and destroyed with greater certainty, including the deepest and best-concealed tunnels through which Hamas smuggles its rockets. Better intelligence might also be gathered by capturing prisoners.

Unless Hamas agrees an imminent ceasefire and the rockets stop flying towards Israel, Gen Eiland predicted that a ground offensive would follow. “I believe that such a decision will be made in the next 48 hours unless there is a surprising twist in the story,” he said.

Any such operation would probably be a limited incursion, not a full-scale invasion designed to re-conquer Gaza. Nonetheless, if the tanks roll into Hamas’s domain, Operation Protective Edge would take another step towards outright war.